A patent search was conducted on this invention and the following United States and foreign patents are noted:
Additionally, the following foreign patents were found:
The Brooks patent discloses a fence post of a stepped design which is not pertinent to the applicant""s invention.
The Marzoli patent discloses a reinforced concrete pole utilizing a central reinforcing bar and wire stands and a mold for constructing same is shown in FIG. 7. No prestressing of the central reinforcing rod is disclosed in this patent. It has a unique shape but not applicable.
The Bensinger patent discloses a concrete fence post which can be screwed into the ground and a wooden strip to support wire fence strands. The tapered concrete post with a tapered bottom with screw threads to aid in getting the post into the ground. No pretensioning is involved.
The Meyer patent discloses a concrete filled tapered tubular tower which may be up to 180 feet in length. However, this post does not have a central reinforcing rod and basically taking an outer steel tower pole or standard 14 and filling it with concrete on location and being filled from a lower inlet port. This achieves a tapered, tubular tower member of considerable strength.
The Engstrom patent discloses a concrete forming apparatus for making fence posts utilizing a batch pour operation similar to a conveyor line production process. A U-shaped reinforcing rod 104 is utilized but no discussion of any prestressing. This patent discloses use of complex and expensive forms.
The Brimhall patent discloses a fence and fence post with removable rail retaining bracket therein teaching square concrete fence posts including a metal rod extended laterally therethrough for attaching to rails 12 and 14 by a cylindrical enclosure 20. This patent teaches a single vertical central reinforcing rod 26 as noted in FIG. 2 but does not set forth any prestressing being involved.
The Harris et al patent discloses tendons for post-tensioned pre-stressed concrete structures having a central reinforcing rod or steel strand 1 that is post-tensioned. This patent teaches the use of an outer sheath 2, a lubricant 3, plus an epoxy resin 11 which would be ruptured on a post-tensioning procedure to create a bond between a surrounding concrete material and the steel strand or reinforcing rod 1. The applicant""s post is xe2x80x9cpre-tensionedxe2x80x9d not xe2x80x9cpost-tensionedxe2x80x9d.
The Sieg patent discloses an anchorage assembly and method for post-tensioning in pre-stressed concrete structures and doesn""t involve a pre-tensioning step.
The Orton et al patent discloses cast concrete fence posts and cast concrete bases for the posts but no pre-stressing is involved.
The Swedish patent discloses a concrete post having considerable reinforcing rods therein and adapted to be stacked on top of each other to obtain the desired height. There are not any prestressing features involved.
The French patent discloses an elongated tapered pole, which may be a telephone pole, and having reinforcing rods therein in the finished form as noted in FIG. 1A. FIGS. 3, 4, and 5 indicate carousel structures operable to hold and space the reinforcing rods in the proper position and placed within each of the protrusions thereabout.
The Japanese patent discloses a structure for reinforced concrete columns having reinforcing rods 3 therein as noted in FIG. 2 embedded in concrete 2 and having an outer square steel pipe 1 thereabout. The strength is achieved by the positioning of the reinforcement rods 3 and no prestressing is discussed in the brief English description.
This invention relates to forms, apparatus, and method procedure steps for mass producing prestressed concrete fence posts, poles, towers, and the like.
The majority of posts used throughout the world are either reinforced concrete, wood, or steel. In earlier times, fence posts were hewn out of sandstone in Kansas where wood is not readily available. The sandstone fence posts are still in wide use in large areas in Central Kansas.
Concrete posts reinforced with deformed non-tensioned re-enforcing bars are now in use, but are larger and heavier than the applicant""s prestressed concrete fence post assembly and are more susceptible to cracking.
Steel posts commonly in use are either galvanized tubes or rolled members of T-shape in transverse cross section. Protrusions are provided at intervals to retain fencing, such as barbed wire secured thereto by wire connector ties. Also, U-shaped plates are secured near a base of the steel posts to resist overturning. The tubular posts are relatively expensive and have no protrusions or means for attaching fence wires. The steel posts are degraded over time by rusting.
Wood fence posts have a finite life due to being deteriorated by rot and insects. Further, the cost of wood fence posts remains high due to a common practice of turning a wood stock to produce a round post having a pleasing appearance and to reduce deterioration by applying a preservative.
Concrete posts currently in use are generally square in transverse cross section, heavier than round posts of equal strength, and are not efficiently manufactured. Prior apparatus and method procedures for making concrete fence posts and poles have not produced products in sufficient quantities at low enough cost to be competitive with wood and steel posts. A method of construction and apparatus to efficiently manufacture concrete posts and poles is therefore highly desirable.
Concrete fence posts made in the manner described in this invention will reduce a factory area required for manufacture, reduce the number of workers required to manufacture the concrete fence posts, and increase the number of concrete fence posts that may be produced in a day to extremely large quantities.
One preferred embodiment of this invention, includes 1) a prestressed concrete fence post assembly and method of construction; 2) a method of construction of a fence post mold assembly; 3) a method of construction of a single prestressed concrete fence post assembly; 4) a method of construction conjointly of a plurality of prestressed fence post assemblies; and 5) a carousel method of construction conjointly of a plurality of prestressed fence post assemblies.
The prestressed concrete fence post assembly includes 1) a main fence post body; 2) a prestressed tendon, cable, or wire strand member positioned centrally of the elongated tapered main fence post body; and 3) a plurality of spaced external connector grooves being parallel to each other and extended longitudinally of the main fence post body.
The main fence post body has a top surface and a bottom or anchor section to be placed within a support medium and having a tapered portion extended upwardly therefrom.
The connector grooves are adapted to receive a connector strand or tie member to attach a fence wire assembly or barbed wire strand thereto.
The method of construction of a fence post mold assembly, which will be used to produce a prestressed concrete fence post assembly, includes 1) a fence post mandrel assembly; 2) a pair of fence post mold half sections; 3) a top end plate member; and 4) a bottom end plate member.
The fence post mandrel assembly includes 1) a mandrel core body member having extended laterally and longitudinally thereof mandrel flange members; and 2) an alignment post at each opposite end thereof to provide a centering feature as will be noted.
Each of the mandrel flange members are provided with a plurality of spaced connector holes operable to be placed internally and secured to the fence post mold half sections as will be noted.
Each fence post mold half section is provided with a mold body member having support flanges secured to and extended outwardly and longitudinally of the mold body member. The support flanges have spaced anchor holes which are adjusted to be aligned with the connector holes in the mandrel flange members.
An angle iron member is welded to upper and lower ends of one fence post mold half section and having flange anchor holes thereon to receive nut and bolt members for anchoring to respective ones of the top end plate member and the bottom end plate member.
As noted in FIG. 10, the top end plate member includes 1) a plate body member having a pair of spaced resin fill holes; 2) a mandrel receiver hole to receive an upper alignment post of the fence post mandrel assembly therethrough for centering purposes; and 3) a pair of spaced connector holes.
The bottom end plate member is substantially identical to the top end plate member having a bottom plate body member having only the connector holes and a mandrel receiver hole therein.
The method steps of construction of a fence post mold assembly includes 1) connecting the fence post mold half sections to each using the nut and bolt members to clamp together, having the fence post mandrel assembly positioned centrally therebetween; 2) attaching the top and bottom end plate members by nut and bolt members to opposite ends of the fence post mold half sections; 3) pouring in a plastic resin material through the resin fill holes in the top end plate member until it is noted that an area therein between the fence post mandrel assembly and inner surfaces of the fence post mold half sections has been completely filled; 4) curing in a temperature and humidity controlled environment until the plastic resin material has been hardened; 5) removing the top and bottom end plate members; and 6) disconnecting the fence post mold half sections from each other such that the fence post mandrel assembly can be removed therefrom.
Each fence post mold half section has an inner liner formed by the plastic resin material which conforms with an outer shape and contour to be created on the prestressed concrete fence post assembly.
In the method of construction of a single prestressed concrete fence post assembly, the applicant follows a first step of connecting final end plate members to a first fence post mold half section having the angle iron support members at opposite ends thereof.
Next, the applicant places a pre-cut tendon member with opposite ends contacting and extended outwardly of the strand access slot in respective ones of the final end plate members.
Next, the other fence post mold half section is secured to the first fence post mold half section by nut and bolt members.
The applicant then utilizes a pair of anchor jaw assemblies, as noted in FIGS. 12 and 13, which are attached to respective opposite ends of the tendon members.
A portable hydraulic prestressing apparatus is connected to the upper anchor jaw assembly which, in turn, is connected to an upper end of the tendon or wire strand member. A hydraulic pressure means is used to the upper anchor jaw assembly to pull the tendon or wire strand member to apply a prestressing force thereon of a predetermined amount. An anchor nut member on the upper anchor jaw assembly is moved into an upper outer surface of the upper final end plate member to maintain the prestressing force on the tendon member.
Next, the applicant injects a special concrete grout material through an inlet spout member in the other fence post mold half section to fill areas between the fence post mold half sections and about the pre-tensioned tendon member.
Then, the applicant proceeds with a curing of the concrete grout material in the fence post mold assembly in an environment of humidity and temperature control.
After the curing has occurred, the applicant disconnects the anchor jaw assemblies and the fence post mold half sections which then allows removal of the final product being the prestressed concrete fence post assembly as noted in FIG. 1.
The fence post mold half sections can be cleansed and reassembled so that the method of producing a single prestressed concrete fence post assembly will be repeated.
The method of construction conjointly of a plurality of prestressed fence post assemblies 6 is noted in FIG. 16 whereupon the applicant provides an assembly line process consisting of 1) filling of a plurality of adjacent ones of the fence post mold assemblies; 2) an automatic station for achieving prestressing of the tendon members; 3) an assembly line method for injecting the concrete grout material within the adjacent fence post mold assemblies; and 4) moving to a curing room area of controlled temperature and humidity. After being cured, the fence post mold assemblies are disassembled, the produced prestressed concrete fence post assemblies are removed, and the respective fence post mold assemblies are moved to the station one for repeating this manufacturing process.
The carousel method of construction conjointly of a plurality of prestressed fence post assemblies involves first interconnecting of a plurality of the first fence post mold assemblies and placing a tendon or strand member within each of the fence post mold assemblies, and means for conjointly applying a prestressing force to the tendon or wire strand members.
Next, the inventor conjointly injects the concrete grout material into the respective ones of the fence post mold assemblies. After curing, the fence post mold assemblies are disassembled and the respective prestressed concrete fence post assembly removed therefrom. Then, the fence post mold assemblies are all disconnected and the prestressed concrete fence post assemblies removed therefrom. This method process can then be repeated.
One object of this invention is to produce a prestressed concrete fence post assembly including a main fence post body having a centrally positioned and longitudinally extended prestressed tendon or strand member therein.
Another object of this invention is to produce a prestressed concrete fence post assembly having a main fence post body with a plurality of parallel, spaced connector grooves that are used with a fence connector tie member to secure spaced ones of fence wire strands thereto.
One other object of this invention is to provide a method of construction of a fence post mold assembly including 1) a fence post mandrel assembly mounted between fence post mold half sections; 2) a top end plate member and a bottom end plate member are connected to respective opposite ends of the interconnected fence post mold half sections; 3) a plastic resin material is injected between the fence post mandrel assembly and the fence post mold half sections; 4) the resin material is allowed to cure; and 5) the fence post mold half sections are disconnected from each other and the fence post mandrel assembly is removed. Then, the fence post mold half sections with the respective inner plastic liner are used with final end plate members to produce the fence post mold assembly used to construct a prestressed concrete fence post assembly.
A further object of this invention is to provide a method of construction of a single prestressed concrete fence post assembly from the concrete post mold assembly involving 1) using the fence post mold assembly in an assembled condition; 2) connecting final end plate members to opposite ends of the fence post mold assembly; 3) placing a tendon member centrally and extended outwardly of each final end plate member; 4) connecting an anchor jaw assembly to each outer end of the tendon or wire strand member; 5) tensioning the tendon or wire strand member; 6) injecting a concrete grout material into the concrete post mold assembly; 7) curing of the concrete grout material; and 8) disconnecting the fence post mold assembly and the final product being the finished prestressed concrete fence post assembly is removed therefrom.
Another object of this invention is to provide a method of construction conjointly of a plurality of prestressed fence post assemblies including 1) placing a plurality of the fence post mold assemblies on a dolly to be moved in an assembly line fashion; 2) placing and prestressing tendon members in each of the fence post mold assemblies; 3) injecting each fence post mold assembly with a concrete grout material; 4) curing the concrete grout material; and 5) removing the finished product of the prestressed concrete fence post assembly.
A further object of this invention is to provide a carousel method of construction conjointly of a plurality of prestressed fence post assemblies whereupon a prestressing of tendon or wire strand members can be done conjointly as well as pouring of concrete grout material. Also, the carousel method operates to open a carousel holding structure so that the plurality of prestressed fence post assemblies can be removed therefrom and the carousel method of construction can be repeated.
One other object of this invention is to provide construction molds to produce a round, tapered prestressed concrete post or pole which is inexpensive to fabricate, durable in usage, and requires minimum personnel and factory space to produce.
One further object of this invention is to provide apparatus and method procedure steps to create a concrete fence post, pole, or tower by rapidly tensioning a centrally located high-strength steel wire cable or tendon member and retaining the tension until a concrete grout material thereabout has attained release strength.
Still, one other object of this invention is to provide equipment and procedures for producing large numbers of prestressed concrete fence posts or pole assemblies in a minimal factory area with a minimum of factory personnel.
Various other objects, advantages, and features of the invention will become apparent to those skilled in the art from the following discussion, taken in conjunction with the accompanying drawings, in which: